A.S.
I agree with the other answers. I would stay off site the last night. We have done this several times even though we did not drive. In fact we usually do this both coming and going - We fly in late one day, say at an offsite hotel, then get up early and start our Disney trip having that first day as a full day in the parks. The coming home we do the same thing - we go to the parks that day leaving our luggage at the luggage counter of the resort. Then at the end of the day we pick up our bags and go to an off-site hotel and fly out early the next morning.
Have fun!